Pencil



G. H. KNIGHT.

PENCIL.

No. 588,867. Patented Aug. 24,1897.

d 111V e'ntor:

. UNITED STATES PATENT OFFICE.

GEoRGE HENRY KNIGHT, OF- LYNN, MASSAcHUsETTs.

PENCIL.

SPECIFICATION forming part of Letters Patent N 0. 588,867, dated August 24, 1897. Application filed. May '7, 1897. Serial No. 635,563. (No model.)

'10 all whom it may concern:

Be it known that I, GEORGE HENRY KNIGHT, a citizen of the United States, residing at Lynn, in the county of Essex and State of Massachusetts, have invented a new and useful Improvement in Pencils, of which the following is a specification.

My invention is a device for a point-maintaining or self-sharpening pencil or crayon.

In this specification graphite or graphite composition may signify any dry solid used for marking purposes which is obtainable of several grades of hardness.

)Vhile applicable to caseless pencils crayons) and available with any suitable marking material, my invention is more especially designedfor, and is here described as, an improvement in black lead-pencils, so called, whose lead or filling is of a graphite composition. My improvement relates wholly to the filling.

My improved filling consists of a slender rod or filament (preferably of graphite or a preparation thereof) which forms the core, center, or nucleus to a surrounding sheath, body, or coating of like but softer material, or to two or more such successively softer concentric layers or coatings. Being applied in a viscous condition said coatings on solidifying unite with the core and with one another to form the closely-adherent mass of soft exterior and relatively hard central portion which constitutes my composite filling.

My invention is illustrated to a greatly-enlarged scale in the accompanying drawings.

Figure Irepresents a core or center. Fig. II represents a completed filling of the simplest binary) form. Fig. III shows the finished pencil, and Fig. IV the same pointed for use. Fig. V represents a multiplex filling, and Fig. VI the same incased. Figs. VII and VIII are cross-sections of the pencils shown at Figs. IV and VI. Figs. IX, X, and XI show a modified construction to a greatlyenlarged scale.

The simplest (binary) form of my filling is seen in Figs. II, III, IV, and VII, in which a core, center, or nucleus at is shown combined with a closelyadherent encircling and supporting shell, sleeve, or coating Z), of softer graphite, which when solidified forms with said core a a composite but solid rod. Instead of being used in this form directly-as a filling the rod a b may receive an added coating 0, Figs. V, VI, and VIII, (or a series ofsuch coatings,) so as to form a multiplex filling. No coating is applied until solidification of the interior portions, and for each addition a softer marking graphite is selected and is applied in a viscous condition. Such application may be made by immersion of the core or solid nucleus in the viscous or semiliquid coating material. Inclosure may take place in the stock or casing 02 before the peripheral or last applied coating of the core has fully solidified. For manufacture of fillings with very slender cores grooved shell partings 12% b, (shown in Fig. IX,) or Z9 00 11 (shown in Fig. X,) or 19% Z), (shown in Fig. XL) being coated with viscous graphite, the core While plastic is placed in groove to and the parts closed together. A still different mode of manufacture may consist in treating the peripheral portions with glycerin or other softoning agent, leaving the hard central portion intact. Cutting into pencil lengths may take place at any convenient stageof the process.

Iclaim herein as new and of my invention- 1. As a new and useful article of manufacture; the point-maintaining pencil comprising a central rod or core of hard marking material and one or more concentric sleeves of successivelysofter marking material in which the rod or core is incased substantially as set forth.

2. A pencil-filling which consists of the combination of a central graphite core a,with an inclosing shell or coating 1), of like but softer material; for the purpose set forth.

3. A pencil-filling composed of the combination of a graphite center a, and the closelyadherent su pportin g-sleeve b, of softer graphite composition; substantially as described and for the purpose set forth.

4. In the described combination; a central core a, of marking material and one or more tubular closely-adherin g coatings b, c, of like, but successively softer material, as set forth.

5. The combination with a suitable casing; bular layers or coatings Z), a, of successively of the composite filling composed of a graphite softer graphite compositions; for the purpose center Within one or more adherent tubes of explained.

a softer graphite composition. GEORGE HENRY KNIGHT.

(3. The described combination with a casing lVitnesses:

d, of a filling, which consists of the graphite M. E. KNIGHT,

core or center (L, and a series of adherent, tu- CHARLES \V. GEER. 

